One lens for A7?

I have the A7 and have been playing with some legacy lenses to get a feel for the A7 without putting out a lot of money. I think I need to get at least one autofocus lens to truly see if I will stay with mirrorless. I am debating on the 35 f2.8, 55 f1.8 or maybe the new 28 f2 when it's available. I also have a 5D3 so this is going to be a small compact full frame point and shoot for now with the hopes of eventually adding other lenses and replacing the big dslr. To keep the cost down I will look for a used 35mm or 50mm. Any thoughts on which will be the best one lens system?

When I was using canon, I had the 35mm f1.4 attached all of the time, and it worked pretty well.

Now that I have sony, my manual focus canon 55mm f1.2 is always attached to the a7r.

I really want to get he 35mm and use it as a walk around lens, 55mm is a bit long but look very very nice.

The 55 1.8 or 35 2.8 are both good choices as AF lenses. Both very good optically. Just need to decide what fits the bill for you in terms of focal length, size, and aperture.

There is no fault in having the Sony/Zeiss FE 55mm f1.8 as a primary lens. It is super sharp. But now that I'm testing the limits of the Sony FE 24-240mm zoom, I have decided it will be my everyday carry and my overseas trip base lens.
See the linked thread for examples:
https://photography-on-the.net …read.php?t=1422​379&page=2

I have the 55 / 1.8 and never took it off my A7S, but when the 35 /1.4 came out, it's never been detached from my camera ever since. It's a great all around lens. They are both keepers, but if I only had one lens to keep, it would be the 35 / 1.4